"There is some research that suggests that, for some kids, weight-related teasing is associated with lower levels of vigorous physical activity," said study researcher Timothy D. Nelson of the University of Nebraska-Lincoln, adding that the reluctance to exercise may be due to fear of being made fun of during activities.

"We tend to think of adolescence as the time when kids become sensitive about their body image, but our findings suggest that the seeds of body dissatisfaction are actually being sown much earlier," said Nelson, who is an assistant professor of psychology. "Criticism of weight, in particular, can contribute to issues that go beyond general problems with self-esteem."

Nelson and his colleagues surveyed 382 public school students with an average age of nearly 11. They calculated participants' body mass index, or BMI, which is a measure of body fatness based on height and weight. Students rated on a 5-point scale how often they had been teased about weight, and general teasing, from kindergarten to the present.

Kids also indicated their current body size and ideal body size on a pictorial scale of seven figures ranging from 1 (extremely thin) to 7 (very obese).

Overweight preteens who endured teasing about their weight tended to judge their bodies more harshly and were less satisfied with their body sizes than students not teased about their weight.

But kids who are overweight might be expected to get teased more (as research has shown) and have more negative thoughts about their bodies than slender children, regardless of the taunting. To figure out how much of the body perception was due to weight-related bullying, the researchers statistically removed the students' BMIs from the equation.

The results held. "In other words, preadolescents who were teased about their weight saw themselves as bigger and were more dissatisfied with their body size than kids who were not teased, even after we accounted for their actual size," Nelson told LiveScience.

To put a stop to the weight-focused teasing, the researchers suggested intervention programs include helping victims develop coping strategies.